In power networks, the double mains frequency produces noise nuisance in the 100Hz and the higher harmonics thereof. Network operators are responsible for a reliable power supply. With the trend to generate energy in a more sustainable way (energy transition), an enormous change is currently taking place in the global power networks. Where in the past, central generation and distribution were used in large power plants, now decentralized generation takes place on land and at sea, including. sun, wind, CHP and biomass. The generated power must be integrated into the existing networks. To this end, a lot of renewal and expansion of the transmission (long distances) and distribution (distribution to users) networks takes place. For grid stability and reliability, the power networks require power transformers and reactors. Important links, but these sources often produce low-frequency noise. With the high demands on people's living and working environment, it is necessary to limit the noise level from these sources as much as possible.